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module Ferret
# Instead of using documents to add data to an index you can use Hashes and
# Arrays. The only real benefits of using a Document over a Hash are pretty
# printing and the boost attribute. You can add the boost attribute to
# Hashes and arrays using the BoostMixin. For example;
#
# class Hash
# include BoostMixin
# end
#
# class Array
# include BoostMixin
# end
#
# class String
# include BoostMixin
# end
module BoostMixin
attr_accessor :boost
end
# Documents are the unit of indexing and search.
#
# A Document is a set of fields. Each field has a name and an array of
# textual values. If you are coming from a Lucene background you should note
# that Fields don't have any properties except for the boost property. You
# should use the Ferret::Index::FieldInfos class to set field properties
# across the whole index instead.
#
# === Boost
#
# The boost attribute makes a Document more important in the index. That is,
# you can increase the score of a match for queries that match a particular
# document, making it more likely to appear at the top of search results.
# You may, for example, want to boost products that have a higher user
# rating so that they are more likely to appear in search results.
#
# Note: that fields which are _not_ stored (see Ferret::Index::FieldInfos)
# are _not_ available in documents retrieved from the index, e.g.
# Ferret::Search::Searcher#doc or Ferret::Index::IndexReader#doc.
#
# Note: that modifying a Document retrieved from the index will not modify
# the document contained within the index. You need to delete the old
# version of the document and add the new version of the document.
class Document < Hash
include BoostMixin
# Create a new Document object with a boost. The boost defaults to 1.0.
def initialize(boost = 1.0)
@boost = boost
end
# Return true if the documents are equal, ie they have the same fields
def eql?(o)
return (o.is_a? Document and (o.boost == @boost) and
(self.keys == o.keys) and (self.values == o.values))
end
alias :== :eql?
# Create a string representation of the document
def to_s
buf = ["Document {"]
self.keys.sort_by {|key| key.to_s}.each do |key|
val = self[key]
val_str = if val.instance_of? Array then %{["#{val.join('", "')}"]}
elsif val.is_a? Field then val.to_s
else %{"#{val.to_s}"}
end
buf << " :#{key} => #{val_str}"
end
buf << ["}#{@boost == 1.0 ? "" : "^" + @boost.to_s}"]
return buf.join("\n")
end
end
# A Field is a section of a Document. A Field is basically an array with a
# boost attribute. It also provides pretty printing of the field with the
# #to_s method.
#
# === Boost
#
# The boost attribute makes a field more important in the index. That is,
# you can increase the score of a match for queries that match terms in a
# boosted field. You may, for example, want to boost a title field so that
# matches that match in the :title field score more highly than matches that
# match in the :contents field.
#
# Note: If you'd like to use boosted fields without having to use
# the Field class you can just include the BoostMixin in the Array class.
# See BoostMixin.
class Field < Array
include BoostMixin
# Create a new Field object. You can pass data to the field as either a
# string;
#
# f = Field.new("This is the fields data")
#
# or as an array of strings;
#
# f = Field.new(["this", "is", "an", "array", "of", "field", "data"])
#
# Of course Fields can also be boosted;
#
# f = Field.new("field data", 1000.0)
def initialize(data = [], boost = 1.0)
@boost = boost
if data.is_a? Array
data.each {|v| self << v}
else
self << data.to_s
end
end
def eql?(o)
return (o.is_a? Field and (o.boost == @boost) and super(o))
end
alias :== :eql?
def +(o)
return Field.new(super(o), self.boost)
end
def to_s
buf = %{["#{self.join('", "')}"]}
buf << "^#@boost" if @boost != 1.0
return buf
end
end
end
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